Damage is good, it requires a TON of power to even fire that thing. The normal formula is 10E:1D and the overcharge formula should be 60E:3D or 20E:1D. I think the stock hulk missile does 900 damage and 9000E, so the overcharged hulk would be 2700D for 54000E. Honestly with the stock hulk missile doing that much damage you are probably better off with an explosive effect to increase the blast radius... (more testing required)
I have not tested anything other than cannons but at least cannon master with a cannon slave consumes 2x energy. That's why my fighter cannot maintain it's guns. Even that being said, I really would like to see the power consumption lowered. 10E:1D means all ships have a 100,000 DPS softcap. My destroyer has 14 million shields on it right now so that means just about every ship out there will take two and a third minutes to punch the shields down (baring use of ION). My destroyer isn't that big and features a full interior, I can't imagine how long fights between two "titans" would take, oh and once you factor in all other power useage you will never get ideal DPS.
Everything is working as intended, of course the intent might be misguided once in practice.